Exemplary embodiments of the invention relate to a steering column arrangement having a torsion damper element and a corresponding assembly method.
It is known from prior art to decouple the vibrations and sounds induced by the chassis in the direction of the steering wheel using a torsion damper arranged in the steering column. During the zero-backlash torque transmission between the output of the steering column and the input of the steering gear, a torsion damper is installed for the integration of vibrations, shocks and forces, which presently does not entirely fulfil the requirements for the damper and decoupling properties.
Conventional torsion dampers consist of a vulcanized elastomer in processed carrier geometries. Pre-processes of blasting and priming are required for the secure adherence of the elastomer, whereby the latter step in the production process is potentially hazardous to human health, and the processing procedure is altogether highly complex.
German patent document DE 10 2008 038 029 A1 describes a coupling device for a vehicle steering spindle, which has an elastic layer between an outer shaft and an inner shaft. German patent document DE 10 2008 038 029 A1 focuses on the constructional design, wherein the covering outer surface of the inner shaft has at least one outer flat region and the covering inner surface of the outer shaft has a corresponding inner flat region. A curve support and a restriction of the torsion angle are therefore provided and torsional reliability is ensured in the case of a defect of the intermediate layer. The corresponding outer and inner surface areas can also be provided in pairs on the covering outer surface of the inner shaft and the covering inner surface of the outer shaft and form a diehedron or a hexagon, for example.
Alternatively to the elastomer torsion damper element, the installation of riveted flexible discs with central bushing is conceivable, however the construction space requirements are frequently not fulfilled.
In view of this prior art exemplary embodiments of the present invention are directed to a steering column arrangement having improved damping properties and good torque transmission between the output of the steering column and the input of the steering gear, wherein the torsion damper should be simple and safe to assemble.
A first embodiment relates to a steering column arrangement having a sliding sleeve and a universal joint yoke, which has a receiving section, in which the sliding sleeve having at least one section is included coaxially. The covering outer surface of the sliding sleeve and the covering inner surface of the receiving section have molded components, such as for example the outer flat regions of the sliding sleeve and inner flat regions of the receiving section known from the prior art for positive connection. Furthermore, a torsion damper element is arranged between the sliding sleeve and the receiving section of the universal joint yoke.
According to the invention, the torsion damper element is formed by an annular arrangement made from an inner carrier ring and an outer carrier ring and an elastomer ring arranged between them, wherein the carrier rings are designed to be elastic in a radial direction and rigid in an axial direction, for example by appropriate choice of materials.
The steering column arrangement according to the invention is characterized by its torsion damper element built as a ring element, which can be installed as a single unit through suitable choice of materials and manufacturing concept. Thus, priming can be avoided and handling during the manufacturing process is simplified. The carrier rings allow for a less complicated assembly of the damper element and additionally the damping properties are improved.
The annular arrangement is pressed onto the sliding sleeve, and the sliding sleeve is pressed with the annular arrangement into the receiving section.
For the accurate axial positioning of the annular arrangement, the sliding sleeve can have an inset or a stopper on its outer covering, which can be formed by an annular collar, by pins or latches. The inset or the stopper located on the sliding sleeve can thereby be provided close to a receiving opening of the receiving section within the receiving section or near the end of the sliding sleeve received in the receiving section. A securing element such as a plate spring or a circlip for securing the annular arrangement is arranged at the end of the annular arrangement facing away from the inset, or is pressed onto the sliding sleeve.
In the receiving section of the universal joint yoke, at least one stepped projection pointing radially inwards is provided on the end facing away from the receiving opening as an inset for the annular arrangement, or above the annular arrangement for the sliding sleeve during the press-in operation.
Furthermore, the steering column arrangement can comprise a further securing element such as a securing ring, which is arranged in the receiving opening, preferably pressed into it. The inset of the sliding sleeve close provided close to the receiving opening of the receiving section can come into contact with this. A tight fit of the securing element can be provided by a remolded material overhang of the receiving section on the receiving opening.
In another embodiment of the steering column arrangement, the sliding sleeve can have an annular groove on its outer covering and the inner carrier ring can have at least one corresponding fastening element on its inner covering, the element having at least one annular collar or at least one latch. Here, the fastening element engages with the annular groove. The outer carrier ring has a radially outwardly protruding annular collar close to the receiving opening of the receiving section, which makes contact with a radially inwardly recessed layer on the covering inner surface of the receiving section close to the receiving opening. Furthermore, the steering column arrangement then also comprises a securing element, such as preferably a securing ring, which is arranged in the receiving opening of the receiving section, such that the outer carrier ring with the annular collar comes into contact with the securing element and is thereby advantageously fixed.
For weight reduction and/or stiffness adjustment, the elastomer ring can have axial keyhole slots as blind holes and/or through holes. For the material of the outer and inner carrier ring a plastic can preferably be used, which provides the rigid design of the same in the axial direction and the elastic design in the radial direction.
In order to form the positive connection between the sliding sleeve and the receiving section, the covering outer surface of the sliding sleeve, the annular arrangement and the covering inner surface of the receiving section can have contours deviating from the circular shape for the formation of the molded components that provide the positive connection. The molded components can be equipped with a many-sided, for example a six-sided, contour or a star-shaped or interlocked contour and are particularly preferably equipped, for example, with six corners or teeth.
Furthermore, the sliding sleeve can have at least one projection protruding radially outwards like an arm, cam or web on its covering outer surface, which is absorbed with clearance in a corresponding recess in the covering inner surface of the receiving section, in order to provide overload protection for excessive steering torques. Thereby, the torque transmission between the universal joint yoke and the sliding sleeve when the projection strikes the recess directly between the universal joint yoke and sliding sleeve and advantageously not via the torsion damper element.
To that end, even two or more projections arranged on the periphery of the covering outer surface can be arranged in pairs opposite to one another or evenly distributed and corresponding recesses can be arranged in the covering inner surface of the receiving section.
Furthermore, the sliding sleeve can have at least two axial grooves located opposite each other on their covering inner surface, with which a spring can engage, which is formed on a single-plated steering spindle part that is to be slid into the sliding sleeve.
The simple assembly method according to the invention for such a steering column arrangement first comprises the provision of the sliding sleeve and a universal joint yoke having a receiving section for the sliding sleeve and the insertion of an elastomer ring between an inner carrier ring and an outer carrier ring for the formation of the torsion damper element designed as an annular arrangement. Here, the inner and outer carrier rings are embodied elastically in a radial direction and rigidly in an axial direction. The annular arrangement is pressed onto the sliding sleeve and the sliding sleeve is pressed in the receiving section of the universal joint yoke together with the pressed annular arrangement. To complete the assembly method, the yoke part of the universal joint yoke is connected to a steering wheel-side counter element and a steering spindle is received in the receiving section.
The torsion damper element presently relates to three basic units, which can be joined simply without further processing; the elastomer of the torsion damper element is located between two plastic carriers, which allow for simple assembly. The specific geometry of the torsion damper element ensures good damping and decoupling properties. The adherence of the elastomer to the plastic is achieved without abrasive blasting and priming.
Further steps of the method according to the invention relate to the axial positioning of the annular arrangement on the sliding sleeve by pressing the annular arrangement onto the inset and the axial positioning of the sliding sleeve with the annular arrangement in the receiving section by pressing onto the stepped projection.
Furthermore, the pressing of a first securing element onto the sliding sleeve on the end of the annular arrangement facing away from the inset and/or the pressing of a second securing element in the receiving opening of the receiving section can take place, wherein, in the latter case, the remolding of a material overhang of the receiving section on the receiving opening can additionally be carried out for the formation of a tight fit of the securing element.
Alternatively, the annular arrangement can be positioned axially during the pressing of the annular arrangement by the fastening elements of the inner carrier ring in the annular groove of the sliding sleeve snapping into place. Furthermore, the sliding sleeve having the annular arrangement in the receiving section is positioned axially during pressing, which is achieved through the laying out of the outwardly protruding annular collar of the outer carrier ring on the radially inwardly stepped level on the covering inner surface of the receiving section close to the receiving opening. The pressing of the securing elements in the receiving opening of the receiving section takes place, and thereby the ribbing of the annular collar and thus fixing in the receiving section on the receiving opening. In this way, a tight and secure fit is advantageously achieved.
These and other advantages are demonstrated by the description below with reference to the accompanying figures. The reference to the figures in the description serves for the simplified understanding of the subject matter. The figures are only a schematic depiction of an embodiment of the invention.